### Please describe the problem.

On a user Windows machine, we get an odd issue of being unable to `annex get` a file from an ssh remote ([https://gin.g-node.org/yarikoptic/test-annex](https://gin.g-node.org/yarikoptic/test-annex)) while using an ssh key with a passphrase.  The reason seems to be that 2nd invocation of `ssh` by git-annex does not result in the prompt for the passphrase.

I failed to reproduce locally in Windows VM machine.  In my case (probably different setup of ssh etc), I 1). get passphrase prompt via external gui window (not in the same terminal); 2). do get 2nd prompt as well.

[Here you can get a full log](http://www.onerussian.com/tmp/test-annex-output-windows-ssh-passphrase-20211209.txt) where you can see passphrase prompt for initial clone, then within `get` once and not after 2nd ssh call


```
$> grep -1 -e passphrase -e faile -e 'ssh ' test-annex-output-windows-ssh-passphrase-20211209.txt
Cloning into 'test-annex'...
Enter passphrase for key '/c/Users/mvdmlab/.ssh/id_rsa':
remote: Enumerating objects: 58, done.
--
# manually added to grep output for more consistent extract
(NWB) PS D:\NWB\test_annex> cd .\test-annex\


(NWB) PS D:\NWB\test_annex\test-annex> git annex --debug get annexed  
--

  Disabling ssh connection caching.
[2021-12-09 10:41:16.7006865] (Utility.Process) process [14232] call: git ["--git-dir=.git","--work-tree=.","--literal-pathspecs","-c","annex.debug=true","config","annex.sshcaching","false"]
--

  You have enabled concurrency, but git-annex is not able to use ssh connection caching. This may result in multiple ssh processes prompting for passwords at the same time.

  annex.sshcaching is not set to true
[2021-12-09 10:41:21.819308] (Utility.Process) process [9560] read: ssh ["git@gin.g-node.org","-n","-T","git-annex-shell 'configlist' '/yarikoptic/test-annex' '--debug'"]
Enter passphrase for key '/c/Users/mvdmlab/.ssh/id_rsa':
[2021-12-09 10:41:32.8083061] (Utility.Process) process [9560] done ExitSuccess
--

  You have enabled concurrency, but git-annex is not able to use ssh connection caching. This may result in multiple ssh processes prompting for passwords at the same time.

  annex.sshcaching is not set to true
[2021-12-09 10:41:32.8443384] (Utility.Process) process [2248] chat: ssh ["git@gin.g-node.org","-T","git-annex-shell 'p2pstdio' '/yarikoptic/test-annex' '--debug' 'dfff8737-36e2-4a1c-8206-bca071a5294d' --uuid 2a0fa804-1bd6-4298-aa55-4dc2d250eeac"]
[2021-12-09 10:41:34.1335084] (Utility.Process) process [2248] done ExitFailure 255

  Transfer failed

--
  No other repository is known to contain the file.
failed
[2021-12-09 10:41:34.1405139] (Utility.Process) process [14104] done ExitSuccess
--
[2021-12-09 10:41:34.1475217] (Utility.Process) process [500] done ExitSuccess
get: 1 failed

```

### What version of git-annex are you using? On what operating system?

Windows, 8.20211124-ga8ff96864

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